Low soot is delivered by using ULSD (Ultra Low Sulphur Diesel) fuel and almost all fuel in UK is refined to that standard - it has nothing to do with the-detergents that are added to the fuel after refining to create the v-power style of fuels.
Many companies call the ULSD fuel City Diesel and you don't need to pay a premium for it. I would also expect that Shell etc would advertise the virtues of Low soot on the V-Power if that were fact, strangely they don't mention it - the manufacturers sites are much more accurate and trustworthy than any wiki
As said before, I ALWAYS use standard diesel, have done for 15 years, and have never had an issue with any of my Volvos - all diesel, or any of the fleet cars that I used before then and we had to use the cheapest fuel.
You call, but 6p per litre is an awful lot extra to pay for fuel, especially when it is not required.